This invention relates to copper (I)-phenoxide complexes, methods for their preparation and methods for utilizing such complexes in producing polyphenylene oxides by the oxidative coupling of phenols.
Polyphenylene oxides, sometimes known as polyphenylene ethers, are well known polymers useful as industrial resins. These polymers, both homopolymers and copolymers, and processes for producing them, are disclosed in U.S. Pat. Nos. 3,306,874; 3,306,875; 3,733,299 and 4,028,341, which are hereby incorporated herein by reference.
These polymers are typically prepared by the oxidative coupling of phenols in the presence of copper-halide-amine complex catalysts. Phenols which can be oxidatively coupled to provide polymers have the structural formula: ##STR1## where X is hydrogen, chlorine, bromine or iodine; Q is hydrogen, hydrocarbon radicals, halohydrocarbon radicals having at least 2 carbon atoms between the halogen atom and phenol nucleus, hydrocarbonoxy radicals and halohydrocarbonoxy radicals having at least 2 carbon atoms between the halogen and the phenol nucleus; and both Q' and Q" are selected from the same group as Q, and, in addition, halogen, provided that Q, Q' and Q" are all free of tertiary .alpha.-carbon atoms.
A number of copper-halide-amine catalyst systems have been disclosed. These are typically prepared prior to polymerization by blending cuprous or cupric oxide with a halide source, usually a hydrogen halide such as HCl or HBr, with one or more amines in the presence of an organic solvent. Suitable amines include tertiary or secondary alkaline diamines, secondary monoamines, primary monoamines, tertiary monoamines and mixtures thereof. Suitable amine mixtures are disclosed in U.S. Pat. Nos. 3,306,874; 3,306,875; 3,941,266; 3,988,287; 4,028,341 and 4,054,553.
In copending application Ser. No. 572,036 new copper (I)-diamine-phenoxide complexes which are useful for polyphenylene oxide preparation are disclosed. These complexes, shown in the formula below, are a single catalyst species which can be prepared in substantially pure, crystalline form. ##STR2## Radical R.sup.1 is hydrogen or alkyl, R.sup.2 is an alkyl radical, with the provisos that (1) R.sup.1 and R.sup.2 taken together contain 4-6 carbon atoms and (2) when R.sup.1 is hydrogen, R.sup.2 is tertiary alkyl, and each of R.sup.3 and R.sup.4 is independently selected from hydrogen or methyl radicals.
Complexes of this structure are prepared by first reacting cuprous chloride with a diamine of the formula: ##STR3## to form a copper (I)-diamine-chloride complex.
The copper (I)-diamine-phenoxide complexes are obtained by reacting an alkali metal salt of a monohydroxy aromatic compound with the copper (I)-diamine-chloride complex described above.
In copending application Ser. No. 652,532, alternative methods for producing these new copper (I)-diamine-phenoxide complexes are described along with methods for preparing a polyphenylene oxide where the complexes are generated in situ.
Although the above diamine-copper (I)-phenoxide complexes are suitable catalysts for the preparation of polyphenylene oxides, these catalysts are produced in two stages. The diamine-copper (I)-halide complex is produced initially followed by subsequent conversion to the copper (I)-diamine-phenoxide complex by the various methods described in the copending applications referred to above. It is desirable to provide a catalyst system for the preparation of polyphenylene oxide which contains a relatively small number of components and is simpler to prepare.
It is also desirable to reduce the nitrogen content of the polyphenylene oxide produced since nitrogen leads to color bodies. The principle source of nitrogen in such polymers is the catalyst system. A catalyst system which incorporates a relatively small quantity of nitrogen would be a distinct advantage.